Scientists have brought back to life microbes found in sediment 100 million years deep from the bottom of the ocean floor. The experiment sheds new light on where life on Earth can be found – and how much it can withstand.
According to a new study published in the journal Nature Communications, microbes found buried under the sea persisted for up to 101.5 million years. Sediments lack the energy needed to allow cells to sustain themselves, but scientists have still been able to revive communities.
It’s a mystery how germs could live in the harsh conditions of their surroundings – and it’s unclear how long they could survive. The researchers said they could possibly be the oldest known organisms on the planet.
Scientists at Japan̵7;s Agency for Marine Science and Technology of the World analyzed sediment samples found about 12,140 to 18,700 feet below the surface of the ocean in the South Pacific Gyre, a system of currents rotating located in the Pacific Ocean. The South Pacific Gyre Center contains “the oceanic pole of accessibility,” the site on Earth farthest from all land – the lowest part of productivity of the whole ocean.
The area has little food, but has plenty of oxygen deep beneath the seabed. The sediment layers, collected during a 2010 expedition, were deposited over a period of 13 million to 101.5 million years ago.
Within the sediment, scientists have found marine microbes: small-celled microorganisms that make up the vast majority of the total mass of living things in the ocean. Trapped in the sediment layers, they could barely move or eat.
The researchers wanted to know if life could exist in an environment lacking such nutrients.
Back in the lab, the researchers were able to wake the germs from their long sleep. They gave the samples of ancient carbon and nitrogen substrates, to test whether they were a feed cable and divide them into more cells.
Over a 68-day period, the vast majority of nearly 7,000 cells responded quickly to the new conditions, multiplied by four orders of magnitude – even in the oldest samples. Researchers said aerobic bacteria dominated the experiment.
“What we found is that life spends all the way from the sea to the basement of the underlying rock,” University of Rhode Island oceanographer and co-author of the study Steven D’Hondt said in a statement of video news. “Those organisms are not only living deep, the oldest sediment, but they are able to grow and divide.”
“It is surprising and biologically demanding that a large fraction of germs can be revived by a very long time of burial or landfill at extremely low energy / nutrient conditions,” author Yuki Morono told Reuters.
Research indicates that microbes can survive for a long time that could not previously be detected if sediment accumulates at a very slow pace, which gets sick in oxygen over time.
Through further experiments, researchers now hope to determine how germs have been able to persist for millions of years.
“The most exciting part of this study is that it basically shows that there is no limit to life in the old sediment of the Earth’s ocean,” D’Hondt told Reuters. “Impressively maintaining full physiological capacity for 100 million years in isolating hunger.”